Packaging, stationary, and other paper-based products are generally manufactured using sheets of raw paper stock or other material that are drawn across presses, dies, punches, or other paper-cutting or paper-forming equipment. Beverage and other cartons, containers, playing cards, signs, placards, corrugated boxes, and other paper or fiber-based or other products are generally formed by contacting a sheet or web of raw material with a punch or die when stripping-out desired areas of material. Such products can also be formed by contacting the sheet or web with a cutting or fold-making blade when generating blanks out of the sheet.
The first process of stripping out holes or sections from the larger piece of material, which leaves a shaped hole and a desired perimeter or outline in the intact paper or other material, is generally referred to as stripping. The second process of cutting or punching a desired shape or section of the sheet entirely out of the sheet and dropping away the removed portion as the desired product, is generally referred to as blanking. In both stripping and blanking operations, the raw feedstock can be in the form of paper, cardboard, plastic, fibrous, or other material, which is conveyed over a working area. The working area can generally include a flat cutting surface or hollow female blanking area over which a blank stock can be contacted with a blade, punch, or other working tool. The sheets are conveyed through work areas on support frames, for example, wooden, metal, or other support frames, which can be sized to conform to the input sheets. The sheets can be conveyed across the stripping or blanking areas using belt drives, linear motors, or other sources of mechanical driving force.
Known stripping and blanking configurations suffer from a number of drawbacks. One drawback can be that the waste portion of the sheet which has been stripped or blanked can jam or snag in the support frame at different points. This can happen, for example, because the sheet dips or sags into open recesses of a blank or die area, catching edges of material on exposed edges in those areas. When a sheet, a knockout, or other waste material produced from a punched or cut sheet, jams in the conveyance path, the machinery may have to be stopped and an operator may need to remove the cut blanks or waste material. Furthermore, the next sheet in the conveyance path can jam against the blocked waste, possibly ruining the next sheet as well.
To attempt to reduce these and other types of material jam-ups, a thin metal element can be attached to the bridge of the work area frame between the recesses, so that a male blanking part, die, or other working tool can be pressed. This lifting type of support is sometimes called a bridge rule. A bridge rule can be comprised of, for example, a plywood stud or other support beam, which supports a sheet of material as it is conveyed over the bridge. However, attaching, orienting, leveling, and maintaining a bridge rule can be time consuming. Metal bridge rules can be subject to damage caused by bending, metal fatigue, misalignment on the beam, or accidental detachment.
Often a male stripping, blanking, or other member or working tool can apply pressure against a sheet that is only supported at the margins, thus causing the sheet to sag. This can cause the tool to partially or totally fail to strip, punch, blank, or otherwise manipulate the sheet when it strikes an unsupported or sagging area. In the case of blanking operations, the blank can fail to separate from the surrounding skeleton (or waste material) and drop free. Jams and hang-ups in the material supply path and incomplete or faulty stripping and blanking operations can waste valuable operator time and effort, cause lost costs from manufacturing downtime, and result in loss of potentially recoverable material. A need exists to eliminate these and other drawbacks in the art.